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-   -   AF 447 report out (https://www.pprune.org/rumours-news/489790-af-447-report-out.html)

Capn Bloggs 18th May 2013 03:39

It's a pity you're not a pilot, Dozy. Then you may undertsand.

Clandestino 18th May 2013 07:16

Oozlum bird is going round, going round, going round....
 
...sang to the tune of "London bridge"


Originally Posted by BOAC
They had a problem. They didn't follow the QRH.

It's even more basic than QRH. They did not understand what was happening so there was no idea what procedure to follow.


Originally Posted by fantome
would ' which incompetence was the root cause of this horrific disaster' be an improvement?

No, it would be wrong. Mere incompetence would not kill them. It was their totally inappropriate reaction that wiped them out.


Originally Posted by Fantom
Am I the first to admit I would have been severely challenged and, probably, overcome by the situation?

No, but even as you are introspecting, you might be quite wrong. There were more than thirty crews faced with the very similar predicament. All of them survived unscathed. In no case that could be analyzed there was execution of prescribed procedure recorded. Some crews were so overwhelmed they kept trying to reengage the AP while the stable aeroplane flew itself out of the ice, speeds returned and re-engagement was successful.


Originally Posted by Fantom
What, in your opinion, is the core issue?

Surprise, shock, horror, followed by the panicky reaction.


Originally Posted by Sunfish
1. Automation must never be totally trusted.

2. It must be possible for the crew to revert to basic mechanical instruments and hand fly the aircraft from first principles.

3. Modifications and upgrades are going to become a nightmare for Airbus because it is impossible to completely understand if new failure modes have been created.

1 and 2 are elements of basic airmanship, 3 is easily dealt with by making the system so good at introduction it needs no major modifications and upgrades. Guess what: there were no major redesigns of FBW in Airbi since they were introduced and FBW Airbi will make a couple of thousands uneventful flights today.


Originally Posted by Sunfish
I expect more of these type of accidents.

What type? Pilots scared out of their wits pulling into stall?


Originally Posted by DozyWannabe
This was well-understood by all the engineers, and if it was not communicated to line pilots, it should have been.

It was certainly communicated via FCOM and self-respecting companies trained their pilots in altn law flying during sim sessions.


Originally Posted by AtomKraft
For Gods sake what harm could be done by linking the sidesticks so they move together?

Severe loss of redundancy as each sidestick now has independent position detection. That infamous DLH incident where roll polarity was reversed in left sidestick with interconnected sticks would left aeroplane with no roll control via sticks at all. As it was, alert first officer disconnected capt's sidestick , took overcontrol and everyone lived on happily instead of cartwheeling into forest just off EDDF 18. My gang insisted that during incap practice we push stick fully outboard and forward, simulating falling on it, so everyone gets practice in taking over the priority. Nowadays if I go lights-out during flight and lean my 220 pounds against the yoke, there is no option for my F/O to just remove my controls from control loop. Something to think about, eh?


Originally Posted by CoolGuys
This is just another generalised summary.

Opinionated and unsubstantiated. Far from being sufficient to be taken into account by aeronautical powers that be.


Originally Posted by CoolGuys
It's a pity you're not a pilot, Dozy.

I am a pilot and I know that "I am a pilot" uttered on anonymous forum is worthless.

nitpicker330 18th May 2013 08:01

Fantom:-- don't use the QRH???? Ha that's funny. We look up the damn complicated thing at least twice a flight for 1/ computer resets 2/ OEB's etc..

A33Zab 18th May 2013 08:41

Linked SS
 

For Gods sake what harm could be done by linking the sidesticks so they move together
With non-linked SS PNF can hold the SS neutral (or rest his hand on SS pedestal), push the red button and direct take over in critical phases when required.

With linked SS, PNF should remove his hand to not obstruct the SS movement.
When it is required to take over, he now first have to visually locate the deflected position of the stick,
grab the stick and initially fight the other stick input.
(and not forget to push the button to disconnect the adjacent SS)

Valuable time is lost and forward facing philosophy interrupted in critical phases.

In AF447 linked SS could have contributed to another outcome but in the majority of airborne time it is completely useless and in critical phases it can be distracted or even dangerous (as described above)

AtomKraft 18th May 2013 09:22

Guys.

If the SS were linked, PNF would have felt (prolly couldn't see) what the PF was doing.
In the panicky atmosphere of those minutes, words lost their impact.
One pilot cocked up, but if the controls were linked it would have needed two pilots to cock up (and stay cocked up) for the accident sequence to continue.

For pitys sake gents- every dual controlled a/c built (apart from Airbusses) has linked controls.

For a bloody good reason.

Rocket science it is not and I think those who argue against it are bonkers.

NIPPI 2000 18th May 2013 09:35


Originally Posted by A33Zab
With non-linked SS PNF can hold the SS neutral (or rest his hand on SS pedestal), push the red button and direct take over in critical phases when required.

With linked SS, PNF should remove his hand to not obstruct the SS movement.
When it is required to take over, he now first have to visually locate the deflected position of the stick,
grab the stick and initially fight the other stick input.
(and not forget to push the button to disconnect the adjacent SS)

Valuable time is lost and forward facing philosophy interrupted in critical phases.

In AF447 linked SS could have contributed to another outcome but in the majority of airborne time it is completely useless and in critical phases it can be distracted or even dangerous (as described above)

I am sorry that I ask, but are you a pilot? Have you operated anything which is classified as airliner? :confused:

Unlinked SS: PF comes in for landing , does the flare pitch wise ok but wings are not level. Me, as PM have to take over by pressing the TO Button. Unfortunately I have no idea now, how much elevator he pulled. So, I have to guess...

The unlinked Sidesticks (and the non moving thrust levers, too) are just downright ridiculous. And so is the QRH, the FCOMs, and and and :ugh:

toffeez 18th May 2013 10:02

NIPPI
 
After how many deliveries do unlinked sidesticks (and the non moving thrust levers, too) stop being downright ridiculous?

With 6800 of these planes now in service, I think the design has earned a bit of credibility.

HazelNuts39 18th May 2013 10:11


Originally Posted by AZR
Is that an "Airbus" design or an "Industry" design, i.e. same situation or comparable airliners (Boeings, Bombardier, Embraer...) ?
This is, I think, a question that was never answered.

It is not a simple question to answer, because it does depend not only on the 'cutoff airspeed', but also on the behaviour of the airspeed measuring system at high angles of attack. The actual airspeed in AF447 probably never went below 100 kCAS. The indicated airspeed went below 60 kt and even to negative values because at extreme AoA the pressures from which it is derived differed so much from the true static and total pressures. That is hardly 'by design', and other airliners may well be different in that respect.

NIPPI 2000 18th May 2013 11:20


After how many deliveries do unlinked sidesticks (and the non moving thrust levers, too) stop being downright ridiculous?

With 6800 of these planes now in service, I think the design has earned a bit of credibility.
.
I would like to see your delivery of your arguments to one of the relatives of the people on board of A447. You could tell them, how good and save this design is - with, after all, 6800 AB FBW flying.

Just do it, after they have been told, that maybe, just maybe, with interconnected SS they might have had a different outcome.

Kids, face it. Airbus went that route because it was more economical and simpler to design non moving Thrust Levers and non connected SS. The present design is not safer - but Airbus (and the relevant authorities around the world) thought it was safe enough.

HazelNuts39 18th May 2013 13:23

Whatever the merits of linked vs unlinked SS are, IMHO the facts do not suggest that the outcome of AF447 would have been different with linked SS,

Up to the point where the airplane stalled, the PNF was aware of what the airplane was doing and that the PF was doing it. If he had felt a need to feel the movements of the SS, feeling those erratic movements would not have added anything to his understanding.

After the airplane stalled, the PNF's understanding of that fact was no better than the PF's and his response to the excessive rate of descent was no different from the PF:

02:11:21 But we've got the engines what's happening?
02:12:13 We're pulling
02:13:40 Climb, climb, climb, climb.

cessnapete 18th May 2013 16:53

fantom
 
The core issue?
BEagle got it right first time.
Plus at all times during the event, the crew had two fully functioning engines, a standby horizon and compass, and a groundspeed readout?????

thermostat 18th May 2013 21:46

I'm quite sick and tired of people who should know better blaming Airbus for this crash. Had there been a different crew flying that night, they would have landed safely. I've said before and will state again:-
a. You don't flying a heavy 'plane (close to coffin corner, at high altitude) into a storm
b. You set up the radar at top of climb
c. You must know the memory items for loss of airspeed drill (and others)
d. You must understand what super-cooled water is and how it can affect your 'plane.
e. As someone pointed out, even if they did nothing, the aircraft is stable enough to right itself. However if you deliberately hold back pressure when you shouldn't, well.............
f. There is no harm in circumnavigating a storm, even if it means making a fuel stop. That's why the pay pilots big bucks, to be SAFE not stupid

This a very sad accident that should never have happened, and I hope by now most of you have learned some valuable lessons from it. I flew the A320 for over 10 years and never encountered any serious problems handling it. If you don't understand your airplane, don't try to fly it. Find something else to do with your life..
Thermostat.

CONF iture 19th May 2013 01:44


Originally Posted by HN39
It will do just that, except when the pilot ignores the stall warning and continues to pull until the AoA exceeds 40 degrees.

At 40 deg AoA the airplane is still stalled so the warning has to keep going.


Originally Posted by A33Zab
With linked SS, PNF should remove his hand to not obstruct the SS movement.
When it is required to take over, he now first have to visually locate the deflected position of the stick, grab the stick and initially fight the other stick input. (and not forget to push the button to disconnect the adjacent SS)

Valuable time is lost and forward facing philosophy interrupted in critical phases.

Such assessment on linked SS is inaccurate.
For the PM the thumb and one finger around the base of the SS would be all it takes to know exactly how the PF is soliciting the other SS.
Valuable time is certainly not lost, but gained.


In AF447 linked SS could have contributed to another outcome but in the majority of airborne time it is completely useless and in critical phases it can be distracted or even dangerous (as described above)
Certainly not useless, distracting or dangerous, but a pure mine of information.
Much improved Situation Awareness.

BEagle 19th May 2013 06:58


I would like to see your delivery of your arguments to one of the relatives of the people on board of A447. You could tell them, how good and save this design is - with, after all, 6800 AB FBW flying.
It's a perfectly good and safe design, provided it isn't being used by people who haven't a clue about what they're doing, who don't have a disciplined flight deck environment and who don't even have a positive handover/takeover control procedure.

PILOT ERROR cause the A447 accident - nothing more, nothing less.

Cool Guys 19th May 2013 07:58


PILOT ERROR cause the A447 accident - nothing more, nothing less.
I dont think anyone disagrees with you. It is pretty clear the accident was due to pilot error. The comments advocating linked sidesticks are about reducing the posibilty of similar accidents by making the controls less susceptable to pilot error, less susceptable to training deficiencies, less susceptable to failures, such a pitot tube blocking, causing confusion etc.

Even in a "perfectly good and safe design" there is always room for improvement.

Oakape 19th May 2013 09:29


Even in a "perfectly good and safe design" there is always room for
improvement.
You have to wonder though, if it's all the 'improvements' that have got us here in the first place. To a certain extent anyway.

FlexibleResponse 21st May 2013 15:01


Quote:
Originally Posted by FlexibleResponse View Post
5. With the subsequent control law reversion, the aircraft was then doomed to a no-stall-recovery situation with the Stabilizer stuck full up (as the Stab autotrim feature was lost with control law reversion). One of the pilots should have re-trimmed the Stabilizer sufficiently nose down with manual inputs using the pitch trim wheel to allow recovery. This did not happen...why?
I'm sorry but that's just wrong. The Stab autotrim feature was never lost in AF447
AlfaZuluRomeo is correct. According to the Accident Report, a reversion to Alternate Law 2B was caused by airspeed "inconsistency" and this mode did not inhibit the THS Autotrim. The THS autotrimmed to 13 deg nose up in response to the PF's aft stick control movements and remained at that value due to the AOA averaging 35 deg during the descent until impact with the sea.

Unusual Attitude Law Reversion was never activated as none of the discrete values were reached.

DozyWannabe 21st May 2013 15:14


Originally Posted by CONF iture (Post 7850175)
At 40 deg AoA the airplane is still stalled so the warning has to keep going.

We went through this in the Tech Log threads - how can the warning keep going if the data required to provide its correct operation is unavailable? You can't just latch it on, because that runs the risk of the warning continuing to sound after the aircraft is out of the stall regime and causing confusion that way.

Capn Bloggs 21st May 2013 15:30


Originally Posted by DWB
You can't just latch it on, because that runs the risk of the warning continuing to sound after the aircraft is out of the stall regime and causing confusion that way.

Obviously you don't latch it on and forget it.

If all the vanes are flopping around in the breeze regardless of the speed, for goodness sake the aircraft must be in a non-flying ie stalled condition. Make the stall warning sound until it is flying again, not switch off below 60KIAS because some boffin thinks "that can't happen". This is not a hard concept to grasp.

DozyWannabe 21st May 2013 16:51

For one thing, it's very hard to detect a "flopping around in the breeze" situation using either analogue or digital means. For another, you're talking about a single failure mode - it might work in an AF447-type scenario, but it won't work in other scenarios - say, if the vane itself fails structurally, or if the cable connecting the vane to the transducer unit fails for whatever reason. This is one of the oldest conundrums in engineering - making sure that an alteration that solves one issue doesn't inadvertently create more problems (as Boeing have been experiencing with their battery issues).

Additionally, this isn't an issue of 'some boffin think[ing] "that can't happen"'. The AoA vanes were supplied with a specification that said they will not function correctly below 60kts IAS - therefore the *aero engineers* wrote the systems specifications to disregard output below that value. According to A33Zab, Boeing's engineers wrote the same specification below 50kts IAS.


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